PSLE
The graph shows the temperature of water in a pot from 1500 to 15 36.
- For how many minutes was the temperature of the water 50°C and below? Give your answer in min.
- During which two 6-minute intervals did the temperature of water decrease at the same rate? Give your answer in the following format. (Eg 01 00 to 01 15, 01 25 to 01 30)
- What was the change in temperature per minute from 1530 to 1536? Give your answer in °C/min.
(a)
Temperature of water that reached 50°C at 15 12.
From 15 12 to 15 36: 24 min
Duration that the temperature of water that reached 50°C and below = 24 min
(b)
Decrease in temperature of water
From 15 00 to 15 06: 80°C - 61°C = 19°C
From 15 6 to 15 12: 61°C - 50°C = 11°C
From 15 12 to 15 18: 50°C - 36°C = 14°C
From 15 18 to 15 24: 36°C - 30°C =
6°C
From 15 24 to 15 30: 30°C - 25°C = 5°C
From 15 30 to 15 36: 25°C - 19°C =
6°C
Two 6-minute intervals that the temperature of water decreas
es at the same rate are 15 18 to 15 24 and 15 30 to 15 24. (c)
Change in temperature per minute from 15 30 to 15 36
= 3 ÷ 6
= 0.5°C/min
Answer(s): (a) 24 min; (b) 15 18 to 15 24, 15 18 to 15 24; (c) 0.5°C/min